Last week wasn't one for the bears. There weren't too many losers, with the Dow, S&P 500, and Nasdaq climbing 1.3%, 1.4%, and 1.7%, respectively. However, there are always tumblers.

Let's take a closer look at five of this past week's biggest sinkers.

Company

April 1

Weekly Loss

My Watchlist

KV Pharmaceutical (NYSE: KV-A) $5.39 (40%) Add
EXFO (Nasdaq: EXFO) $8.23 (26%) Add
SmartHeat (Nasdaq: HEAT) $2.68 (22%) Add
A123 Systems (Nasdaq: AONE) $6.12 (21%) Add
Krispy Kreme (NYSE: KKD) $5.56 (16%) Add

Source: Barron's.

Shares of KV slipped after the drugmaker announced a sharply lower price for Makena, its recently Food and Drug Administration-approved preterm labor prevention treatment. This is good news for pregnant women and potential preemies, but not a welcome development for shareholders, who had bid up the stock under the assumption that Makena would be selling for $1,500 a pop.

EXFO may have reported sales growth for a sixth consecutive quarter, but the market wasn't impressed. The financials posted by the optical test and service assurance solutions provider for the telco industry fell well short of Wall Street expectations. There were also concerns about a sequential dip in orders.  

March wasn't a hot month for SmartHeat, as its stock tumbled 38% last month. SmartHeat appears to be in the right place at the right time; the Chinese maker of plate heat exchange systems has choice seats for the clean energy revolution. However, whispers of accounting irregularities have taken down many of the smaller Chinese equities. There is no proof that SmartHeat's numbers are suspect, but risk and volatility are rocking the boat. Just last month, SmartHeat was targeting a profit of $0.60 a share to $0.80 a share this year. If it's able to clear the cynicism hurdle, the shares are too cheap to ignore.

A123 ran out of juice after announcing a highly dilutive secondary offering. The maker of lithium-ion battery packs had a strong IPO less than two years ago, powered by the shift toward more fuel-efficient cars. Reality hasn't been as kind. Lackluster financials and a disappointing outlook for 2011 have weighed on the stock.

Finally, we have Krispy Kreme not making the dough go nuts. Its latest quarter showed ho-hum comps and a slip in guest counts. The chain is hoping to push through a modest price increase, but that's a questionable strategy if the "Hot Doughnuts Now" sign isn't as magnetic as it used to be.

It was a rough week for these five stocks. Let's see which ones bounce back this week.

Which of these five stocks do you think bottomed out last week? Share your thoughts in the comment box below.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.